Wireless phone systems are commonly used in PBX serviced areas as well as in the public cellular phone system. Wireless voice systems are designed to allow only registered mobile phones to originate-and receive calls. This presents a problem when the user must make an emergency call while traveling in an area which is serviced by a phone system in which the user is not registered. Current protocols in some wireless voice systems (e.g., DECT systems) allow an unregistered mobile phone to make a call if the call is designated as an "emergency call". However, current protocols do not allow an unregistered mobile phone to receive a call for any reason.
When an emergency call is received by a telephone system, it is typically forwarded to an Emergency Service Answering Point (ESAP) where a specially trained operator handles the call. If the ESAP loses the connection to the caller, the ESAP may not be able to provide emergency service without re-establishing the telephone link. If the call was placed from the public switched telephone network (PSTN), the emergency operator receives the number of the telephone making the call from the telephone system, and hence, can call the party back to continue the call. Furthermore, the emergency operator can determine the location from which the call was made since the telephone number is associated with a unique geographical location.
Such call backs are not possible with current wireless systems since an unregistered telephone does not have a phone number in the system. In public cellular systems, the limited amount of information that can be transferred to the ESAP forces further compromises usefulness. In these systems, the location of the caller is deemed to be more important than a call-back number. Since the systems are set up to transfer only a single identifying number, the cellular systems transfer a number identifying the antenna on which the call was received. This provides some localization of the user; however, this location information is, typically, limited to localization within a few miles. If the call was transferred to another antenna because of congestion at the closest antenna, this localization information is even less usefil.
Broadly, it is the object of the present invention to provide an improved wireless telephone system.
It is a further object of the present invention to provide a wireless telephone system in which an unregistered telephone can make an emergency call and receive a call back from an emergency operator.
It is yet another object of the present invention to provide a wireless telephone system in which the emergency operator can receive both location and call-back information.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.